If anyone wants to try RPCEmu (0.8.100) on RISC OS it can be downloaded from here.

It just needs a RISC OS rom dropping in the ‘roms’ folder then it will boot into the dekstop.

Things missing.

1. No keyboard input. (missing support in the Qt5 libraries). The workaround is to use VKeyboard or Keyboard as an on-screen keyboard.
Create Obey files for things not possible with the mouse. e.g. filer_opendir $.!Boot.
2. No sound. (missing audio backend in the Qt5 libraries)
3. No Networking.
4. HostFS works non-natively. Zip up everything before copying into the hostfs folder. Then unzip on RPCEmu.

Tested with RISC OS 4 and 5 on Titanium, RPi 3 and IGEPv5. Aemulor also works albeit very slowly. (Needs RISC OS 5.22 and RPCSA as the CPU)

Also download resources.zip and merge the contents into !Boot. These are the same files used for Otter Browser and QupZilla. If already using either of these browsers there is no need to download resources.zip.

It works very well under RISC OS 5. For RISC OS 4.02, it boots in supervisor mode. You’ll need a ready to run system (Boot, etc.) in order to get a normal boot. Mouse tend also to disappear on the host.

At a guess that’s because you already ran the RPCEmu with RO5.x and the CMOS settings for RO5.x are still there and don’t match what the 4.02 install requires.
As a test I’d create a working 4.02 install elsewhere and copy the cmos file from that into the RPCEmu on RO install.